Method of covering wires



NOV- 17, 1936- M. M. J. E. couPlER Er AL 2,051,350

METHOD OF COVERING WIRES Filed May 22, 1935 Patented Nov. 17, 1936 UNITED STATES PATENT orrlcl:v

METHOD oF covEmNG wmEs Application May 22, 1935, serial No. casse In France May 29, 1934 13 Claims. (Cl. 205-18) Electric resistances, conductors or cables are now in use wherein the insulating material consists of a mineral powder enclosed by any suitable external covering. A

Such cables, which possess the great advantage of being incombustible, are usually manufactured in one of two ways. Thel more simple manner consists in disposing in a metallic tube, the cylinder or cylinders constituting the conductors,

then filling the hollow space between the tube and the conductors with the mineral powder, and thereafter submitting this assemblage to a lengthening treatment say by rolling or drawing. Another manner giving rise to successful results consists in forming the mineral powder in situ; for example magnesium strips are wound round the conductors or wires and are disposed inside the outer sheath, tube or the like; then a current of steam is caused to ilow inside said sheath; the

magnesium is thus transformed into magnesia; which expands and entirely lls the hollow space remaining between the conductors and the inner wall of the sheath. This assembly may then be submitted to the mechanical lengthening treatment as above.

The first of the above disclosed procedures presents the drawback that it is very difficult to prevent the conductors from being displaced slightly with reference to the sheath during the diierent operations, so that the cable consequently is not exactly centered.

The present invention is directed to an improved method of manufacture of cables of this kind, and consists in disposing the insulating material around the conductors after having iirst imparted to this material the form of elements of compressed powder the said elements retaining the conductors in their respective places. When it is l desired to manufacture only a relatively short rough piece of cable which must be subsequently lengthened it is possible to use elements shaped as cylinders and provided with holes through which are engaged the metallic bars which are intended to serve as the conductors; likewise, if

it is desired to prepare long rough pieces or even true cables, each of the above disclosed elements are divided into several parts by longitudinal sections, say plane or helical, and said parts are juxtaposed on the conductors and are held in their 5o places by a suitable sheath such as a metallic tube, a braiding, a covering or the like.

The following disclosure with reference to the annexed drawing indicates by-gway o! example different forms of execution of the invention.

' 55 Figure 1 is a-perspective view of an element used in a rough piece intended to be lengthened for producing a cable having three conductors.

Fig. 2 is a cross-section of a rough piece for a cable having a single conductor.-

Figs. 3 and 4 are cross-sectional views showing 5 elements capable of being interlocked with each other.

Fig. 5 shows part of an elementcapable of being used either vfor a rough piece intended to be lengthened or for true cable of considerable 10 length.A

Fig. 6 shows how the parts of elements illustrated in Fig. 5 may be used for manufacturing a continuous cable.

Fig. 7 is a perspective View of an element having 15 a helical section.

Fig. 8 shows an element of modified shape.

In order to prepare a short rough piece which is to be further submitted to a lengthening process as by drawing, rolling or any other mechanical method, it is possible to use cylindrical blocks formed of compressed powder, provided with apertures through which are engaged the metallic bars which are to serve as the conductors.

Fig. 1 shows such a block designed to be used 25 in a cable having three conductors; Fig. 2 shows a rough piece prepared for manufacture by lengthening an insulated conductor covered with a tu- .bular sheath.

On a conductive stem i of copper, are disposed 30 cylindrical elements 2, made of compressed powder, similar to those of Fig. 1 with the exception that they are each provided with a single aper-lI ture instead of with three. These blocks or elements are formed from mineral powder, which is 35 compressed in moulds by any suitable machine, 'the powder at that time being either dry or wetted in order to produce a dough.

The assembly is surrounded by a sheath 3, say a lead tube, whereupon the nal assembly is 40 lengthened by a suitable mechanical process such as rolling, drawing, or the like; during all those operations the elements 2 keep the conductor l centered in the axis of sheath 3, and as a consequence of the lengthening operation, these ele- 45 ments are crushed and the mineral material returns to its original state; i. e. reduced to powder.

- In .order to increase the coherency of the elements, they may be soaked before use in a suitable solution such as boric acid. It is also possible to provide the apertured blocks on their inner or outer ends or both with very thin sheaths of 'either metal or paper the thickness of which is negligible with reference to the other dimensions o! the element, the central bore 55 thereof remaining of course uncovered. In assembling the cable, it is advantageous to dispose the sheath inside the moulds before the powder is compressed therein to form the elements, or if desired, the sheath may also be applied around a. previously prepared element. FinalLv the sheath may also consist of a suitable coating which becomes solid upon drying.

' In order to prevent the elements from being displaced sidewise with respect to each other. it is possible to impart to them such a shape that they interlock. Fig. 3 shows several elements interlocked with each other byvirtue of their frusta-conical joints 1. The se elements are shown as encased in inner and outer sheaths l and 9 of suitable material, say in paper.

Fig. 4 shows in cross-section a single element provided at one end with a spherical central recess and at the other end with asimilarly shaped projection, so that the projection of one element may penetrate in the recess of the following one.

'I'he elements are always provided with inner and outer sheaths l and 9. It is moreover obvious that many other shapes might be provided for and those shown in the drawing are simply by way of example.

The procedure of engaging the apertured elements on the conductive bars obviously can be applied only for short bars; fit is thus possible to prepare in this manner only rather short rough pieces which are to be changed by lengthening into resistances or cable sections. However it is impossible to use this method when the elements are to be disposed around conductors which afterwards are to be submitted to only a slight lengthening treatment or are even not to be lengthened at all.

In this last case the elements are divided into several parts by longitudinal sections. For instance it is possible to divide elements such as those shown in Fig. 3 or 4 by one or more planes either passing through the axis or avoiding said axis in order to lengthen the leak lines capable of passing through the joints. By leak lines we mean the path followed by the current in passing from the conductor to the outer sheathing between the insulating elements. Fig.- 5 is a perspective view of one half of an element I3 similar to that represented in Fig. 4.

Fig. 6 shows by way of example how a single wire cable provided with an external braiding may be manufactured in a continuous manner by means oflparts of elements such as those represented in Fig. 5.

Wire I is driven in a continuous manner in the direction of the arrow; during its progression it penetrates elements il, i2 similar to those of Fig. 5 so that these latter are disposed around it. The figure shows an element Il just ready to be positioned in place, the assembly is wrapped with a braiding I4, say of textile material, by means of any convenient known machine. The elements such as i3 are disposed on the wire just at the point where the braiding is woven into position. It is easy to see in the gure that the elements are kept in place at the same time by being intcrlocked by means of their projections and receases and by being enclosed in the braiding. 0f course it would be better to stagger the planes forming the joints of the consecutive elements with reference to each other.

In order to prevent the elements from sliding on each other, the sections, instead of being planes, may be given the shape of helical surfaces, and moreparticularly that of square threaded screws, or better of helical surfaces the generatrix of which remains parallel to those of a cone but do not meet the axis, in order to lengthen the leak lines passing through the joints. Fig.-

7 represents an element similar to that illustrated in Fig. 4 but divided into two parts in the manner suggested above.

The elements could of course each be divided into any desired number of parts by such helical sections.

More particularly a shape may be imparted to the parts of elements which is limited on the one hand by cylindrical surfaces and on the other hand by square threaded screw surfaces as illustrated in Figure 8.

What we claim is:

1. A proceeding for manufacturing electric insulated conductors with an external sheath and a mineral insulating material consisting in preparing elements with a compressed powder of the insulating material, said elements being disposed between the conductors and sheath and the whole being then submitted to a mechanical lengthening treatment.

2. A proceeding as claimed in claim 1 wherein the compressed elements are soaked in a solution increasing their cohesion.

3. A proceeding as claimed in claim 1 wherein 'the elements are provided with at least one aperture so disposed as to be capable of being engaged on bars adapted to become conductors after lengthening, the external cylindrical surfaces of the element being covered with a thin llayer of suitable material.

4. A proceeding as claimed in claim l wherein the elements are provided at least. with one aperture disposed to be able to be engaged on bars intended to become conductors after lengthening, the surface of the apertures of the element being covered with a thin layer of suitable material. y

5L A proceeding as claimed in claim 1 wherein the elements are provided at least with one aperture disposed to be able to be engaged on y bars intended to become conductors after lengthening, the external surface of the element and the inner surface of the apertures of the element being covered with a thin layer of suitable material.

6. A proceeding as claimed in claim 1 wherein the elements are provided at one end with a recess and at the other end with a similarly shaped projection.

'1. A proceeding as claimed in claim 1 wherein the elements are provided at least with one aperture disposed to be able to'be engaged on bars intended to become conductors after lengthening. the external cylindrical surface of the element being covered with a thin layer of suitable material, the elements being provided at one end with a recess and at the other end with a similarly shaped projection.

8,. A proceeding as claimed in claim 1 wherein the, elements are provided at least with one aperture disposed to be able to be-engaged on harsv intended to become conductors after lengthening, the surface of the apertures of the element being covered with a thin layer of suitable material, the elements being provided at vone 'end with a recess and at the other end with a similarly shaped projection.

9. Aproceedingasclaimcdinclaim 1 wherein theelementsareprovidedatleastwithone bars intended to become conductors after lengthening the external surface of the element and the inner surface of the apertures of the element being covered with a thin layer of suitable material, the elements being provided at one end with recess and at the other end with a similarly shaped projection.

10. A' proceeding as claimed in claim 1 -wherein each element is divided in several partsdi'sposed to be applied against one another round the conductor. a

11. A proceeding as claimed in claim 1 wherein each element is divided in several parts by planes. l '12. A proceeding as claimed in claim 1 wherein each element is divided in several parts so.

disposed as to be capable of assembly together about the conductor, the sections being shaped as helical surfaces.

13. A proceeding as claimed in claim 1 wherein each -element; is `divided in several parts so disposed as to be capable of assembly together about the conductor, the sections being shaped as helical surfaces, each element being provided at one end with a recess and at the other end 10 with a similarly shaped projection.

' MARCEL MARIE JOSEPH EUGENE commen.A

JosUE RODOLPHE HEIIMANN. CHARME'. EMMANUEL MILD. 

